Mexico City sinks every year mainly because it is built on an old lake, Lake Texcoco, and excessive extraction of groundwater to meet its water needs has caused the ground to sink.
Mexico City is situated in a basin surrounded by mountains, and originally, there was a series of shallow lakes. Over the millennia, these lakes filled with sedimentary deposits like clays and silts. This mixture of loose soils makes the ground unstable, much like a huge wet sponge. Over time, these sediments gradually compact under the weight of buildings and when groundwater is pumped in large quantities. As a result, the geological structure of the basin, primarily made up of a fairly thick layer of clayey sediments, greatly facilitates land subsidence. Essentially, we live on a large soft and sponge-like surface, which is clearly not ideal for a growing megacity.
Beneath Mexico City, the water used by residents mostly comes from huge underground natural reservoirs called aquifers. Due to intensive extraction to meet the growing needs of this vast city, these aquifers no longer have time to recharge naturally from rainfall. The result: the ground loses its support, like a sponge filled with water that is gradually being squeezed. Less groundwater means a drop in pressure and a settling of the layers of earth above. This phenomenon, known as subsidence, largely explains why Mexico City sinks several centimeters each year.
Mexico City is built on an ancient lake filled with clay soils, a material that has the unfortunate characteristic of being able to compact significantly when it loses its water. Imagine a big wet sponge: as long as it is saturated with water, it remains voluminous and firm, but as soon as it dries, it shrinks and loses volume. This is exactly what happens here: by pumping water from underground aquifers for their needs, the residents gradually remove this moisture from the clay. As a result, the layers of clay compact, and the surface ground begins to sink, leading to a slow but certain gradual subsidence of the entire city, sometimes by more than 10 cm per year in certain neighborhoods! This compression phenomenon is irreversible: even if pumping were to stop immediately, the clay would not regain its original volume.
The subsidence in Mexico City poses serious risks to the residents and infrastructure of the city. Each year, this phenomenon severely damages buildings, roads, the subway, and even disrupts gas and water networks. As a result, many homes develop cracks or become outright unstable, directly threatening the safety of individuals. Financially, the bill is steep: constant repairs heavily burden municipal budgets, reducing the funds available for other important public services like health or education. In some neighborhoods, the gradual sinking of the ground also increases the risk of flooding. Consequently, the most modest residents, often living in vulnerable areas, find themselves more exposed, exacerbating social inequalities.
The city is focusing on better water management, including projects to naturally recharge aquifers, by promoting infiltration instead of paving everywhere. A serious approach involves significantly reducing groundwater extraction by connecting more neighborhoods to external sources, such as reservoirs located further away. Many efforts are also aimed at repairing leaks in the drinking water network—which are very numerous in Mexico City— to prevent waste. Some experts are even exploring the idea of directly injecting treated water underground to stabilize fragile soils. Finally, in urban planning, programs are currently raising public awareness to adopt water-saving practices to relieve underground reserves.
The phenomenon of subsidence in Mexico City began as early as the colonial era with the Spaniards, who gradually drained the surrounding lakes and inadvertently increased the instability of the site.
According to some scientific estimates, since the beginning of the 20th century, certain parts of Mexico City have lost up to 10 meters in elevation due to the intensive pumping of groundwater.
Originally, Mexico was built on a lake, Lake Texcoco. To establish the city, the Aztecs initially created an ingenious system of dikes, canals, and floating gardens called chinampas.
The gradual subsidence of Mexico City regularly causes cracks in the infrastructure, significantly disrupting the networks for drinking water distribution, electricity, and even the stability of historical structures.
The fact that Mexico City was built on the reclaimed site of an ancient lake partly explains the fragility of the clayey soil, which compresses easily when the water from the underlying aquifers is pumped intensively. This particular geological structure exacerbates the current subsidence.
Although it is not literally at risk of completely disappearing underground, specific areas could become uninhabitable or will require very costly lifting and consolidation work if no action is taken quickly to curb the causes of subsidence.
The subsidence is very difficult to completely reverse. However, it can be significantly slowed down through sustainable groundwater management, artificial recharge of these aquifers, and the implementation of appropriate urban policies.
No, other major cities like Jakarta, Venice, and Bangkok are also experiencing a similar phenomenon due to a combination of groundwater extraction, rapid urbanization, and specific geological structures.
The subsidence leads to problems such as cracking of buildings, destruction of urban infrastructure (pipelines, roads), increased risk of flooding, and very high economic costs for repair and maintenance.
Some areas of Mexico City are currently sinking at a rate of up to 30 cm per year, mainly due to the intensive extraction of groundwater.
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